A 48-year-old man was left in critical condition after an argument on a Red Line CTA train escalated to a fight Monday night on a platform where he was stabbed, Chicago police said. About 10:30 p.m., police responded to a fight on a Red Line CTA platform in the 500 block of North State Street. During the fight a 31-year-old man pulled out a sharp object and made contact with the older victim, .